DE3134782A1 - AUTOMATIC ADJUSTING DEVICE FOR IMAGE QUALITY IN A COPIER - Google Patents

Description

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G 52 885

Automatic picture quality adjustment device in a copier. . .

The invention relates to an apparatus for automatically adjusting the image quality in an electrostatic Recording apparatus such as copier and others, and particularly adjustment apparatus (Adjustment device) that automatically adjusts the density of the copied image according to the density of a background color and an image density of the original.

In general, it is beneficial if the background color a copy made by an electrostatic recording device such as a copier and others is generated, regardless of the background color / of the original, the background color of the copy paper, namely represents a white background. However, if the density of the copy is adjusted so that that to be copied Original with a comparatively dark background color becomes a white background, for example, the contrast decreases and the image quality of the copy deteriorates when copied an original to be copied with light-colored images such as pencil writing. ■.

Currently many copier devices have a built-in manual device for adjusting the density, and the operator makes a test

copy to the most suitable density or adjust based on experimental experience, but so far it has been impossible to avoid wasting copies.

To increase speed and increase effectiveness of copying, on the other hand, copiers with an automatic original feeder have recently become popular (ADF facility) spread quickly and in the case of using numerous originals for Copy, like in an ADF facility, is for the. · Almost impossible for operators of a copier to have a Device for adjusting the density to be handled every time the didhteconditions of the copied Originals change if the originals whose background. . color and image density are each different, mixed be, and even if it is possible, the. Work of the operator complicated, and accordingly the benefit of automation is diminished.

In contrast, facilities were recommended at. which determine the density of the original to be copied. and the picture quality is automatically adjusted '(JA Patent Application Laid-Open No. 93834/1978 and other). In these cases, however, the density state is controlled by the maximum value and the minimum value of the density , and therefore it is possible that with an original with an image that is darker than the one on it, most of all required image, like an original written in pencil with a line mark and others, the density state based on the line marking can be set, which is inconvenient.

According to the invention, the density distributions become the background color and the image on the original to be copied

detected by scanning the original to be copied, and thereby the density state is to be automatically adjusted such that the relationship of density between the background color and the copied image, where the copied image is most visible, can be adhered to.

The attached figures are briefly explained below.

Figure 1 is a plan view showing an example of the invention;

2 shows an example of the levels of signal resp.

■ reporting procedure; -. '

Figure 3 is a basic view of the density measuring circuit (or density discriminating or selecting circuit, hereinafter referred to as density measuring circuit);

FIG. 4 shows a series of histogram representations, according to various. Types of originals were made;

Figure 5 shows a flow sheet of assessments;

Figure 6 is a block diagram of a control circuit; .

FIG. 7 shows a correspondence circuit for the non-judgmental case; and

Figure 8 provides an illustrative example of the operation of the correspondence circuit shown in Figure 7.

The following are preferred embodiments of the invention described. "Reference is made to the attached figures

took.

Figure 1 shows a plan-like drawing that a Fig. 3 shows an example of the copier with an ADF device; an electrostatic latent image is created of the photosensitive substance of the drum 1 is formed at the exposure part 2 and developed at the developing part 3 and the image density is adjusted by the bias voltage applied to the developing member 3. ·

/ ") · In the ADF device 6 are fed originals 5 "*" * 8 sheet for sheet fed to the exposure section. According to the invention the density distribution of the original -4 when passing through a sensor for the reflectivity 7 of Type of reflection detected. There is a scanning in perpendicular to the direction of insertion of the original 4 by the feeler guide device 9 and the feeler 7 represents the reflectivity of the background color, the Letters, figures and images on the original. The output information of the sensor 7 represents the mean value the amount of light reflected in the area of the irradiated. And if the diameter of the spot is compared with the density distribution (e.g. line width of the. - ** ·> letters) the image information is relatively large, so shows the probe '7 has a reflectivity which is greater than the image part, as the mean value of the density on the area of the spot, and thus it is impossible to determine the density distribution of the original. Therefore, it is necessary to make the diameter of the spot small for the determination. The output information of the sensor 7, which is used for this, .should be linear in the area of the density distribution ■ change the original. As the sensor 7 to be used for this purpose, an image sensor and others become easy Handling is used, but reflectivity sensors of the reflection type can of course also be used other types can be used.

The output information of this probe 7 can be obtained in a waveform in time series corresponding to the image density on the irradiation scanning point. This output information is received in the sampling circuit 10 and is then measured by the density measuring circuit or selective circuit 11 as to which section of the previously established density classification it belongs to, and the output information corresponding to the density classification becomes the counter-.lerschaltung 12 sent. The sampling circuit 10, as described later, samples the output information waveform of the probe 7 in the preset mode, and the sample number of each density classification within the scanning area of the original is counted by the counter circuit 12 and the density histogram the density classification of the original is established. . / ⁺ _{or #} sampling circuit

Depending on the difference in the special nature of the original, namely the difference between the original from one • Invoice book and a note with dark pictures against a white background coloring and the one created with pencil Original with a comparatively dark background color and others, the histogram can be special Characteristics corresponding to such a difference can be obtained, and therefore the picture quality control part 13 controls the developing part 3 by controlling the bias of the Magnetic brush presetting 14 according to the mode of the previously established histogram in such a way, that the color of the ground is brought close to white Decrease the copy density in the colored ground of the to original to be copied, and images will be more emphasized by increasing the copy density of the original. with a white Background and bright images.

The following is the function of each of the foregoing parts

will be explained in more detail, and FIG. 2 represents "an illustrative one Diagram for sampling from the output information

• tion of the sensor 7 represents the sensor output information that obtained by scanning the diagram a of the figure is shown in c of the figure »The sharpness on the rising-

. the part of the output information is, as mentioned above, influenced by 'the diameter of the irradiation spot at the edge of the density distribution b.'

This sensor output information is displayed on the sampling tray 10, .and for this sampling are the method of sampling with a constant cycle for the Sampling period and the method of sampling with the maximum value and the minimum value as well as the circuit for the realization of which is known. "Door the former, however the density classification distribution contributes to an apparent increase in the mean density fraction. the sampling at the intermediate part between rising and falling output information signal, as in the figure 2d, where the sampling points are indicated by black circles. In the latter case it is

• On the other hand, the number of samples taken is too low, as in the. Figure 2e, and there is a problem that the .Specifying the background color of the original, difficult is. Accordingly, in the present example, the sampling takes place with a constant cycle, as shown in FIG. 2f.

. and at the same time the sample is also taken with Extreme values - which is a mixed method of both methods. If, however, only originals of one type are used, then, for reasons of simplification, the sample. ■ would take place according to the maximum value and minimum value.

The output information thus extracted is used by the density measuring circuit or selective switching 11. measured accordingly, which section of the density classification, which is set to 8 levels, for example, it belongs to, and becomes

is supplied to the counting circuit as output information corresponding to each classification. An example of this' The measuring circuit is shown in FIG. In the figure, Vc represent the generator source for the standard voltage and R represents a resistor for dividing the standard voltage, and connection points' for each resistor represent the Represent tensions that fix each density of the eight levels. In addition, Ci represents a measuring circuit and receives the output information signals from the probe 7, with an input power through the sampling circuit, • which has an amplifier A and an electronic switch S, and it generates pulses, depending on which Level 1 to 8 corresponds to this signal, and the pulses are entered into the counter circuit for counting.

In the above example, the density classification determined by the density measuring circuit 11 after the samples was taken by the sampling circuit 10, however Of course, sampling can be done after the step waveform is first passed through the density measuring circuit was set up.

In this way, the density information is sampled, which was obtained by scanning the original, according to • a fixed mode and is measured or selected in 8 stages, and the output information from the measuring circuit is counted and stored by the counting circuit, whereby the histograms shown on the right-hand side of FIGS. 2d-f are formed. According to the invention, the Counting a few previously determined density classifications, and so it follows that the storage capacity, which is required for the formation of the histogram can be 'low'. ·

The histogram thus obtained shows a characteristic pattern depending on the kind of the original. If the original is a

The invoice book and a slip of paper indicate the density classifications, which correspond to the paper background color and the letter image, a comparatively high frequency and the peaks are formed in these areas. at on the other hand, a halftone original such as a photographic original is distributed without special Peaking. As a typical pattern for the original of an invoice book and slip of paper, FIG. 4 shows the density histogram in three types of a) a printed original with a white background, b) a printed one Λ '\. · ■ Original with colored background and c) one with lead.

*? * ' with the original written on with a pen. white background. In the . In comparison with the histogram of the printed original on white background in a) ', the peak on the left side corresponding to the background color density of the colored original such as colored paper and newsprint original moves to the high density portion as shown in FIG the. FIG. 4b shows what is based on the low reflectivity of the background color; on the brightly colored image such as a pencil original and others, the peak on the right side corresponding to the image moves to the low density portion as shown in c of the same figure. In the present example

^ _n , the picture quality control circuit 13 _{# is located in} accordance with the patterns of these histograms, biases,. which have been previously determined according to each pattern, to the magnetic brush, and thus the image quality is adjusted. In the case of the printed original with a colored background, in comparison with the printed original with a white background (normal), the background color is brought close to white by the development of light, which is due to the increase (high) of the bias, and in the case of the light original image with a white background the bias for the dark development is decreased (low) to make the image clear even if the background color is dark to some extent

is made. FIG. 5 shows how the evaluation is carried out. In Figure 5, levels 1 and 2 represent a white back • background level and level 3 a colored background; levels 4 and 5 represent light images and levels 6 to 8 represent dark images.

The image quality control circuit 13 is included for this purpose a CPU core 15 as shown in Figure 6. CPU 15 operates in accordance with ROM 16 in which the processing routine is programmed. The assessments of the established Histogram pattern generates control signals for the image density, and the display device 17 can set copying conditions can be displayed as required.

In the assessment model shown in Figure 5, if an assessment is not possible, especially in the case of the not possible assessment 2 and 3, also copying are interrupted, and a warning signal on the display 17, so that the judgment to an operator of the copier can be left to. In the case of non-assessability 1 can be considered, for example there will be a moment when the information is insufficient to determine the conditions, as only something there is less than one line of letters on an original to be copied. In a case like the one above, it is It is reasonable to keep the copy conditions for the previous original "as such". The circuit and the The operating status for this to implement the controls, as mentioned above, are shown in FIGS. 7 and 8, respectively.

Accordingly, as shown in FIG. 7, D Flip-flop circuits D1-D3 introduced into a circuit for controlling the signal output information. As is well known D flip-flop circuits read a signal which is fed into a data input information terminal D,

when a clock pulse has been delivered, and then accumulate this signal until the next clock pulse is given. The copy start signal and a judgment completion signal are fed in through the AND gate D and serve as a clock pulse. If 1 cannot be assessed, switch S is closed. With reference to FIG. 7, at ti at the level of the judgment output information "low", a bias voltage by the output information of D flip-flop D3 controlled, but in t2 D3 is set to the zero level by the next copying start signal and the judgment completion signal is returned, and alternatively, the judgment output information becomes "normal" by D flip-flop Di is read in, and thus the copying conditions are determined. In T3, if 'the next original turns out to be non-verified proves divisible 1, the switch S by the output information signal of the non-assessable closed, and the input information of the clock pulse becomes zero, and thus, the D flip-flop is held in its state, whereby the judgment output information is in the normal state and thus copying under the same conditions as for the previous original can be done.

In the specific example, the operation takes place as mentioned above, but the invention can be modified in various ways. be fified. In the specific example, the default setting for the developer brush was used as the • Density setting device is used, appropriately set, · but. - does not have to be explained in more detail that an image control. also by adjusting the amount of light from a projection lamp, the diaphragm value of exposure, the volume of charge a photosensitive drum, etc. can be done.

A device with an ADF device was also used in the example described, but the invention can also be used with a copier of the type of movable original

Glass plate, and a further embodiment can be in a copier of the type of movable, optical system by "splitting the light- ■ path on the way of an optical system for exposure or by scanning the surface potential of a drum that has been exposed.

Depending on the circumstances, there are also cases where "it is favorable control copy-image quality to suit various purposes. Wiaxl, for example, copied a drawing, like this The demands of the users of the copy vary with whether the line lines of a piece of paper or a writing paper should or should not be visible on a copy. In a case like the one above, it is possible to set so that. they can be made visible or invisible by switching the lip switch LS and then 'by changing over the resistor UR, as in Figure 3 ■ shown. For example, the switch LS becomes brighter switched, the divided voltage delivered to the resistor UR is lower, and the reference voltage that each Level-equivalent is then decreased, creating a Background color that corresponds to level 2 as a level 3 is judged and a level 5 image is judged to be level 6; as a result, one changes Control signal output information from "low" to "high", and the image therefrom becomes lighter in density, so. that the line lines that represent the lighter image are undeveloped and invisible in a copied image will. If the switch LS is switched to "darker", the opposite occurs.

■ This switch LS can be operated manually, as described above, can be switched, but this can also be done automatically by determining the conditions, such as the ambient temperature, the humidity, the toner density, the lamp

'- 17 -

Deterioration and the like each having an influence on the image density of a copy.

By the present invention differing from the usual Technology differs, it is possible to automatically make the most constant to achieve suitable image density that corresponds to the characteristics of different originals; this becomes through it . enables the density distributions of an original to be processed statistically.

Claims (1)

Dr. Ing.Dr. jur. F. Dr. rer. nat. B. Dr. rer. nat. D. DiplMwgi.Oh. ■ vREDIES REDIES TURK & G ^ Ji ³ L ^ PATENT LAWYERS Professional Representatives boforo ' the Europoan Pötont Öflic «. Telephone (0211) 7150 39 Telex 8582 841 rrtg d Telegrams: Returgi Düsseldorf Bruckner Street 20
D-4000 Düsseldorf 13 Your sign: Our sign: Date: Konishiroku Photo Industry Co., Ltd. No.26-2 Nishishinjuku 1-chome Shinjuki-ku, Tokyo, Japan G 52 885 Automatic picture quality adjustment device. in. a copier ".. ' .. ". . Claims 1. Automatic adjustment device for image quality in a copier, comprising: Facilities for determining the density of an original to be copied, KonlC-n: Duutache Dnnk AQ., DOsaoldorf. (ÖL? 300 70010) Account no. C033 516 Slndtspalkasr.o Düasoldort, (EJLZ 300 501 10) KoMo no. KSOOO 9M ThO Sanwa Bank Ud. Düssoldorf, (D ₁ LZ 301307 00) account no. 00128? Postal check Cologne 666 01-502 (BLZ 370 100 50) Means for forming a histogram accordingly the density distribution of the density determined with the detection devices, and Means for setting a fixed image density using the pattern or scheme of Histogram. " 2. Automatic picture quality adjustment device . according to claim 1, in which the locking device is a Image sensor is. 3. Automatic picture quality adjustment device according to claim 1, in which the locking device is a Reflectivity sensor is. 4. Automatic picture quality adjustment device according to claim 1, 2 or 3, in which the educational institutions a device for sampling the output information from the detection devices and comprise a density measuring device for measuring the output information. 5. Automatic picture quality adjustment device according to "claim 1 or one of claims 2 to 4, in which the means for adjusting a developing device comprise. 6. Automatic picture quality adjustment device according to claim 5, wherein said developing device comprises a magnetic brush and a magnetic brush presetting means for controlling the pre-tensioning. 7. Automatic picture quality adjustment device according to claim 6, wherein said developing device further comprises an image quality control part to control the advance voltage of the magnetic brush. Presetting device includes. 8. Automatic adjustment device for the image quality in a copier containing Devices for determining the density of an original to be (~) 'copied, ■ ^: Means for forming a histogram according to the density distribution of the detection ' Facilities determined density, Means for setting a fixed image density using the pattern or scheme of the Histogram, and if this pattern of the histogram obtained is outside the one previously set, Facilities to indicate this. 9. Automatic adjustment device for the picture quality '■ £ according to claim 8, wherein the detection means are an image sensor. · ■■ jp. Automatic adjustment device for the. Picture quality · according to claim 8, wherein the detection means is a reflectivity sensor. 11. Automatic adjustment device for the picture quality according to claim 8, 9 or 10, wherein the educational facilities a device for sampling the output information from the detection devices and a density measuring device for measuring them Output information. ο Automatic adjustment device for the image quality according to claim 8, 9, 10 or 11, in which the setting means comprise a developing device. 13. Automatic picture quality adjustment device according to claim 12, wherein the development device . a magnetic brush and a magnetic brush preset device includes to control the bias. 14. Automatic image quality adjustment device according to claim 13, wherein the developing device further comprises a part for controlling the image quality to control the bias of the magnetic brush presetting device includes. 15. Automatic image quality adjustment device according to claim 8f in which the device furthermore Devices for interrupting or setting the ■ copying operation includes. 16. Automatic adjustment device for · the image quality in a copier, containing: Means for determining the density of an original to be copied,
/ Means for forming a histogram in accordance with the density distribution of the determination devices provided by these determined density, and a device for measuring density - for formation of the histogram, means for setting a predetermined image density using the Patterns or schemes of the histogram and facilities - to change the setting density on the density measuring device. 17. An automatic picture quality adjuster according to claim 16, wherein said determining means are an image sensor. ■ '. 18. Automatic picture quality adjustment device according to claim 16, in which the determining means are a sensor for reflectivity. KJ ' 19. An automatic image density adjusting device according to claim 16, 17 or 18, in which the forming means a device for sampling the output information from the fixing devices and a density measuring device for measuring this Aus ^ include delivery information. ·. 20. Automatic picture quality adjustment device . according to claim 16, 17, 18 or 19 in which the adjustment devices comprise a development device. f ·} 21. Automatic picture quality adjustment device. ' according to claim 20, in which the developing device comprises a magnetic brush and a magnetic brush preset device for controlling the bias. . · 22. Automatic adjustment device for the image quality according to claim 21> in which the developing device also has a part for controlling the image quality to control the bias of the magnetic brush presetting device includes.